Abstract: The new Virtual Mission concept will provide NASA's Science Program with a powerful new, 'go-as-you-pay,' flexible, and resilient way of accomplishing its science observing program. The concept will foster the use of smaller and lower cost satelites. It will enable the fleet of scientific satellites to evolve in directions that best meet prevailing science needs. It will empower scientists by enabling them to mix and match various combinations of in-space, ground, and suborbital instruments - combinations which can be called up quickly in response to new events or discoveries. And, it will enable small groups such as universities, Space Grant Colleges, and small businesses to participate significantly in the NASA space program by developing the discrete components of this evolving space fleet. Future Earth and Space Science Missions are addressing increasingly broad and complex scientific issues. To accomplish their objectives, these NASA missions need to acquire and coordinate data sets from a large number of different instruments, to coordinate multiple measurements of the phenomenon of interest, and to coordinate the operation for the many individual instruments making these measurements. Our new concept will respond to these needs by enabling multiple instruments to work together and therefore be employed as a single mission - or a 'Virtual Mission.' A mission in which multiple scientific instruments will generally be on different platforms, in different orbits, operated from different control centers, at different institutions, and reporting to different user groups. Before this Virtual Mission concept can be implemented, techniques need to be developed to enable separate instruments to work together harmoniously, to execute observing sequences in a synchronized manner, and to be managed during coordinated activities by a Virtual Mission authority. Enabling technologies include object-oriented design approaches, extended operations management concepts, and distributed computing techniques.